Heterochromatin of the Drosophila melanogaster Y chromosome as modifier of position effect variegation: the time of its action. |
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Authors: | Hans Joachim Becker and Wilfried Janning |
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Institution: | (1) Zoologisches Institut der Universität München, Luisenstr. 14, D-8000 München 2, Federal Republic of Germany;(2) Zoologisches Institut der Universität Münster, D-4400 Münster, Federal Republic of Germany |
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Abstract: | Summary Addition of heterochromatin suppresses while subtraction enhances position effect variegation. The heterochromatin-sensitive period has been determined in white/white-apricot variegated eyes of Y
S
w
a
/w
a
; Dp (1;3) w
265-58 flies. When such larvae, carrying a Y-short (Y
S
) arm at the distal end of one X chromosome, are X-rayed, mitotic recombination leads to one daughter cell with two Y
S
arms and an adjacent daughter cell with no Y
S
arm. When induced after clonal initiation, the frequency of dark clones developing from daughter cells with two Y
S
arms is significantly higher than the frequency of dark clones in the rest of the eye; and this frequency is. even higher when induced before clonal initiation. The modifying action of the Y-heterochromatin is exerted, therefore, during and after clonal initiation. Surprisingly, the frequency of dark clones developing from cells with no Y
S
arm is not lower than the frequency of dark clones in the rest of the eye. |
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Keywords: | |
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